You should establish a baseline power measurement before you tune your server for energy efficiency.
If your server has the necessary support, you can use the power metering and budgeting features in Windows Server 2012 to view system-level energy consumption through Performance Monitor (Perfmon). One way to determine whether your server has support for metering and budgeting is to review the Windows Server Catalog. If your server model qualifies for the new Enhanced Power Management qualification in the Windows Logo Program, it is guaranteed to support the metering and budgeting functionality.
Another way to check for metering support is to manually look for the counters in Performance Monitor. Open Performance Monitor, select Add Counters, and locate the Power Meter counter group. If named instances of power meters appear in the box labeled Instances of Selected Object, your platform supports metering. The Power counter that shows power in watts appears in the selected counter group. The exact derivation of the power data value is not specified. For example, it could be an instantaneous power draw or an average power draw over some time interval.
If your server platform does not support metering, you can use a physical metering device connected to the power supply input to measure system power draw or energy consumption.
To establish a baseline, you should measure the average power required at various system load points, from idle to 100 percent (maximum throughput). Such a baseline generates a “load line.” Figure 2 shows load lines for three sample configurations.
Figure 2. Sample load lines
You can use load lines to evaluate and compare the performance and energy consumption of configurations at all load points. In this particular example, it is easy to see what is the best configuration. However, there can easily be scenarios where one configuration works best for heavy workloads and one works best for light workloads. You need to thoroughly understand your workload requirements to choose an optimal configuration. Don’t assume that when you find a good configuration, it will always remain optimal. You should measure system utilization and energy consumption on a regular basis and after changes in workloads, workload levels, or server hardware.
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